Resilience To Stress Plays Role in Depression

"An individual’s emotional response to severe, acute stress (e.g., trauma, terrorist acts) or to more prolonged chronic stress (e.g., divorce, war-time torture) is determined by genetic and environmental elements that interact in complex and poorly understood ways... A majority of humans exposed to stressful events do not show signs of psychopathology such as posttraumatic stress disorder (PTSD) or depression... However, the neural substrates and molecular mechanisms that mediate resistance to the deleterious effects of stress remain unknown."

~ Krishnan et al

Results of a new study reported in the journal Cell may lead scientists along the path toward learning how to enhance a naturally occurring mechanism in the brain that promotes resilience to psychological stress. Studying a mouse model, researchers funded by the National Institute of Health's National Institute of Mental Health (NIMH) found that the ability to adapt to stress is driven by a distinctly different molecular mechanism than the tendency to be overwhelmed by stress. The researchers mapped out the mechanisms — components of which also are present in the human brain — that govern both kinds of responses.

In humans, stress can play a major role in the development of several mental illnesses, including depression and post-traumatic stress disorder. A key question in mental health research is: Why are some people resilient to stress, while others are not? This research indicates that resistance is not simply a passive absence of vulnerability mechanisms, as was previously thought; it is a biologically active process that results in specific adaptations in the brain's response to stress.

Vulnerability was measured through behaviors such as social withdrawal after stress was induced in mice by putting them in cages with bigger, more aggressive mice. Even a month after the encounter, some mice were still avoiding social interactions with other mice — an indication that stress had overwhelmed them — but most adapted and continued to interact, giving researchers the opportunity to examine the biological underpinnings of the protective adaptations.